RFR: 8372564: Convert StringDedup to use Atomic<T> [v2]

[Kim Barrett]

> Please review this change to StringDedup to use Atomic rather than directly
> applying AtomicAccess to volatile members.
> 
> Testing: mach5 tier1-5

Kim Barrett has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Merge branch 'master' into stringdedup-atomic
 - remove use of DeferredStatic
 - Merge branch 'master' into stringdedup-atomic
 - stringdedup uses Atomic

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/28524/files
  - new: https://git.openjdk.org/jdk/pull/28524/files/a14d77ce..01c0b461

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28524&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28524&range=00-01

  Stats: 59697 lines in 1039 files changed: 37648 ins; 16991 del; 5058 mod
  Patch: https://git.openjdk.org/jdk/pull/28524.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28524/head:pull/28524

PR: https://git.openjdk.org/jdk/pull/28524